dup: now forbid to (try to) backup /

ChangeLog

@@ -33,6 +33,7 @@ version 0.9.4 -- unreleased
 	   any passphrase
 	 . Support duplicity 0.4.2 (with Debian patches applied; upstream's
 	   0.4.3 will integrate them)
+	 . Now forbid to (try to) include /.
 	sys:
 	 . Many more system checks were added, thanks to Petr Klíma
     lib changes

handlers/dup

@@ -144,6 +144,7 @@ done
 	
 # includes 
 for i in $include; do
+   [ "$i" != "/" ] || fatal "Sorry, you cannot use 'include = /'"
    str="${i//__star__/*}"
    str=`readlink -f $str`
    if [ -n "$str" ]; then